namespace StackExchange.Redis
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Net;

    public static class StackExchangeRedisExtensions
    {
        public static IEnumerable<IServer> GetMasterServers(this IConnectionMultiplexer connection)
        {
            var endpoints = GetFilteredEndpoints(connection);

            var allServers = endpoints.Select(ep => connection.GetServer(ep));

            var masters = allServers.Where(s => !s.IsSlave).OrderBy(s => s.EndPoint.GetPort().Value);

            return masters;
        }

        public static IEnumerable<EndPoint> GetFilteredEndpoints(this IConnectionMultiplexer connection)
        {
            var endpoints = connection.GetEndPoints();

            if (endpoints.Count() > 1)
            {
                var instanceEndpoints = endpoints.Where(ep =>
                {
                    var port = ep.GetPort();
                    return port.HasValue && port != 6379 && port != 6380;
                });

                if (instanceEndpoints.Any())
                    return instanceEndpoints;
            }

            return endpoints;
        }

        public static int? GetPort(this EndPoint ep)
        {
            int? port = null;

            if (ep is DnsEndPoint)
                port = ((DnsEndPoint)ep).Port;
            else if (ep is IPEndPoint)
                port = ((IPEndPoint)ep).Port;

            return port;
        }

        //AZURE REDIS SPECIFIC IMPLEMENTATION
        public static int GetShardIdForKey(this IConnectionMultiplexer connection, string key)
        {
            var slot = connection.HashSlot(key);
            var masters = connection.GetMasterServers();
            var x = masters.First().ClusterNodes().GetBySlot(slot);
            return GetShardIdFromPort(x.EndPoint.GetPort().Value);
        }

        //AZURE REDIS SPECIFIC IMPLEMENTATION
        public static int GetShardIdFromPort(int port)
        {
            return (port % 100) / 2;
        }

        public static async void FlushAllNodes(this ConnectionMultiplexer connection)
        {
            foreach (var server in connection.GetMasterServers())
            {
                await server.FlushAllDatabasesAsync();
            }
        }

        public static string Info(this IServer server, string sectionName, string item)
        {
            return server.Info().SubSection(sectionName).SubItem(item);
        }

        public static IGrouping<string, KeyValuePair<string, string>> SubSection(this IGrouping<string, KeyValuePair<string, string>>[] info, string sectionName)
        {
            var section = info.Where(g => g.Key == sectionName).FirstOrDefault();
            return section;
        }

        public static string SubItem(this IGrouping<string, KeyValuePair<string, string>> section, string item)
        {
            if (section == null)
                return null;

            var listEntry = section.Where(g => g.Key == item).FirstOrDefault();

            return listEntry.Value;
        }
    }
}